Regulation of Gene Expression

Question 1

Explain differential gene expression

Answer 1

the expression of different genes by cells with the same genome. (370)

Question 2

What are the general stages of Gene expression in order?

Answer 2

(371) 1. Signal to chromatin, chromatin modification(DNA unpacking),
2. Gene available for DNA transcription, Transcription into primary transcript
3. RNA processing into exon with cap and tail
4. This mRNA goes from inside the nucleus into the cytoplasm
5. Translation occurs then mRNA degradation happens as the polypeptide is formed,
6. Polypeptide into active protein by protein processing
7. Active protein is transported to designated location as an enzyme and proteins undergo degradation

Question 3

What is histone acetylation?

Answer 3

Chomatin has histone tails protruding outward. These are binding sites for enzymes of acetyl , methyl, and phosphate groups for gene regulation. (371)

Question 4

What is DNA methylation?

Answer 4

other than histones, gene regulation can occur directly in the DNA……different sets of enzymes can methylate the DNA itself on certain bases, usually cytosine. This is DNA methylation (371)

Question 5

What is epigenetic inheritance?

Answer 5

Inheritance of traits transmitted by mechanisms not involving the nucleotide sequence itself is called epigenetic inheritance. (372)

Question 6

What are control elements?

Answer 6

segments of noncoding DNA that serve as binding sites for the proteins called transcription factors, which bind to the control elements and regulate transcription. (373)

Question 7

What is an activation Domain? explain purpose

Answer 7

Activation domains bind other regulatory proteins or components of the transcription machinery, facilitating a series of protein-protein interactions that result in enhanced transcription of a given gene. (374)

Question 8

What are enhancers?

Answer 8

The more distant distal control elements (374)

Question 9

What is a DNA-binding domain?

Answer 9

a part of the protein’s three-dimensional structure that binds to DNA—and one or more activation domains. (374)

Question 10

How do different cell types develop differently from others? ex: liver and lens cells

Answer 10

Control elements activation expresses different genes.

ex: liver cells expressing albumin gene and lens cells expressing crystalline. (375)

Question 11

What is alternative RNA splicing?

Answer 11

regulation at the RNA-processing level:

different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns. Regulatory proteins specific to a cell type control intron/exon choices by binding to regulatory sequences within the primary transcript. 377

Question 12

whare are ncRNAs?

Answer 12

Non-coding RNAs 379

Question 13

What are microRNAs (miRNAs)?

Answer 13

small, single-stranded RNA molecules capable of binding to complementary sequences in mRNA molecules. 379

Question 14

What are siRNAs?

Answer 14

small interfering RNAs which are noncoding RNAs 380

Question 15

What is RNA interference (RNAi)?

Answer 15

The blocking of gene expression by siRNAs 380

Question 16

What is differentiation?

Answer 16

the process by which cells become specialized in structure and function. Moreover, the different kinds of cells are not randomly distributed but are organized into tissues and organs in a particular three-dimensional arrangement. 381

Question 17

What is morphogenesis?

Answer 17

the development of the form of an organism and its structures. 381

Question 18

What are cytoplasmic determinants?

Answer 18

Maternal substances in the egg that influence the course of early development 382

Question 19

What is induction?

Answer 19

the signals conveyed to an embryonic cell from other embryonic cells in the vicinity, including contact with cell-surface molecules on neighboring cells and the binding of growth factors secreted by neighboring cells (see Concept 11.1). Such signals cause changes in the target cells, a process called induction 382

Question 20

What is determination?

Answer 20

the point at which an embryonic cell is irreversibly committed to becoming a particular cell type. 382

Question 21

What is pattern formation?

Answer 21

Cytoplasmic determinants and inductive signals both contribute to spatially organizing the tissues and organs of an organism in their characteristic places. This developmental process is referred to as pattern formation. 384

Question 22

What is positional information?

Answer 22

The molecular cues that control pattern formation 384

Question 23

What are embryonic lethals?

Answer 23

mutations with phenotypes causing death at the embryonic or larval stage. 385

Question 24

What is a maternal effect gene?

Answer 24

cytoplasmic determinants in the egg are the substances that initially establish the axes of the Drosophila body. These substances are encoded by genes of the mother, fittingly called maternal effect genes. A gene classified as a maternal effect 386

Question 25

What are morphogens?

Answer 25

Gradient of substances that establish an embryo’s axes and other features of its form. 387

Question 26

What are oncogenes?

Answer 26

Cancer causing genes 388

Question 27

what are proto-oncogenes?

Answer 27

The normal version of the oncogene that encodes for normal cell growth and development. 388

Question 28

what are tumor-suppressor genes?

Answer 28

genes that inhibit abnormal and harmful cell growth.

Question 29

Explain the RAS gene

Answer 29

encodes for the RAS protein which is a G protein that relays a signal from a growth factor receptor on the plasma membrane to a cascade of protein kinases. The cellular response at the end of the pathway is the synthesis of a protein that stimulates the cell cycle 389

Question 30

What is regulation?

Answer 30

Genes are turned on and off in response to signals from their external snd internal environments.

Question 31

What is an operon? How do they work?

Answer 31

An operon is a functioning unit of genomic DNA that contains a group of genes controlled by a single promoter. Put simply, these genes share information needed to create the tools for a particular task so they share a promoter ensuring they’ll all be transcribed together.

Question 32

Heterochromatin vs euchromatin

Question 33

Why is Chromatin structure important in gene regulation?

Answer 33

the structure of chromatin influences what genes are expressed by…..the location of the nucleosomes along the promoter and sites where DNA attatches to the protein scaffolding on chromosome. Also genes with packed heterochromatin are usually not expressed. (blockage)

Question 34

Histone acetylation ____ transcription and DNA methylation ____ transcription

Answer 34

Promotes, reduces

Question 35

Transcription factories

Answer 35

areas in Nucleus where transcription occurs.

three parts work together: chromatin loop, transcription factory and the chromosome territory.

Question 36

what is transcriptional control?

Answer 36

regulation of transcription is the major step in gene control. Control is exterted primarily at the level of initiating transcription.

Question 37

what two things are needed for transcription control?

Answer 37

control elements and activators.

Question 38

What is a mediator proteins?

Answer 38

proteins that interact with the general transcription factors at the promoter.

Question 39

What is the TATA box?

Answer 39

Smaller region on the promoter next to a gene. binding site for the tata binding protein.

Question 40

Explain the steps leading to RNA polymerase transcribing DNA

Answer 40

RNA polymerase needs transcription factors and activators to bind to enhancers that will bend toward the promoter allowing the RNA polymerase to bind to the promoter with assistance from all these parts. This will then allow RNA polymerase to transcribe.